I am trying to free up some space on my laptop's hard disk and am using a tool (SpaceMonger) that will show me a treemap of the whole disk.

The problem I have comes from Live Messenger's SimilarityTable2 file. I have no idea what it is for, but I know that it is a sparse file, meaning that it shows as taking up 8GB of disk space, but actually only takes up 132KB of space on disk. The problem is that because SpaceMonger thinks this file is 8GB, it swamps the other files and takes up most of the treemap, making it hard to see the other files that really are large.

Is this file safe to delete? If not, how do I make its actual size on disk match its reserved size? If that's not possible, how can I make SpaceMonger (or another treemap tool) use the real size of the file and not the reserved size?

EDIT: I've just realised that I have some NTFS junctions set up, meaning that the same set of directories appear twice. Is there any way to stop this happening as well?